[CATALITICAL PROPERTIES OF LIVER MONOAMINE OXIDASE IN THE CHUM SALMON ONCORHYNCHUS KETA].

The substrate and inhibitory specificity of mitochondrial monoamine oxidase (MAO) in the liver of males of the summer form of the chum salmon Oncorhynchus keta was studied. As to the spectrum of deaminated substrates, the hepatic MAO of the chum salmon is similar to MAO of most terrestrial mammals, for eight classical MAO substrates similarity in their substrate characteristics were found. Analysis of the antimonoamine oxidase activity of two derivaties of 2-propinilamine, five derivatives of acridine as well as of pyronine G revealed significant qualitative and quantitative differences as compared to the hepatic enzyme of tuna and whitefish. The compounds tested manifested themselves as irreversible inhibitors of chum salmon's hepatic MAO possessing various efficacy, but lacking the selectivity of action as dependent on the deaminated substrate. The obtained data on the substrate and inhibitory analysis provide an indirect evidence for the presence of a single molecular form of MAO in the chum salmon liver.

[The reactivity of liver monoamine oxidase in the ringed seal Phoca hispida ladogensis].

The goal of the work consisted in study of substrate and inhibitor specificity of liver monoamine oxidase (MAO) of the freshwater Ladoga subspecies of the ringed seal Phoca hispida ladogensis. The studied enzyme has been established to have large substrate specificity by deaminating, apart from eight classic substrates of MAO of terrestrial mammals, also histamine, the diamine oxidase substrate. It is found out that the deamination rates of benzylamine, beta-phenylethylamine, and N-methylhistamine almost one order higher than rates of deamination of serotonin and noradrenaline. MAO of the seal liver does not deamnate putrescine and cadaverine and is not sensitive to 10(-2) M semicarbazide. We calculated bimolecular constants of interaction rates of inhibitors chlorgiline, deprenyl, berberine, sanguinarine, chelidonine, and four derivatives of acridine with the enzyme at deamination of nine substrates. By the method of the substrate-inhibitor analysis, we showed the enzyme heterogeneity, i. e., the existence in the seal liver of at least two different MAO.

[Liver monoamine oxidase activity of the lamprey Lampetra fluviatilis. the substrate-inhibitory specificity].

Based on data of substrate-inhibitory analysis with use of specific inhibitors--deprenyl, chlorgi-lin--and specific substrates--serotonin, noradrenalin, benzylamine, beta-phenylethylamine, and N-methylhistamine--a suggestion is put forward about the possible existence of one molecular form of monoamine oxidase (MAO) in liver of mature individuals of the European lamprey Lampetra fluviatilis. There are determined kinetic parameters of monoamine oxidase deamination of eight substrates, which indicates the large spectrum of substrate specificity of the lamprey liver MAO. The studied enzyme does not deaminate histamine and putrescine and is not sensitive to 10(-2) M semicarbaside. Results of study of the substrate-inhibitor specificity allow us to suggest some resemblance of catalytic properties of the lamprey liver MAO and the mammalian form A MAO. The revealed low activity of the enzyme at deamination of all used substrates seems to be connected with low detoxational functional of the lamprey liver.

[Enzymological characteristics of liver monoamine oxidase of the skipjack tuna Katsuwonus pelamis].

There has been carried out a study of substrate and inhibitor specificity of the liver mitochondrial monoamine oxidase (MAO) of the striped-bellied tunny Katsuwonus pelamis. Results of the substrate-inhibitor analysis with use of chlorgilin and deprenyl are an indirect proof for the existence in the tunny liver of one molecular MAO form. The studied enzyme, like the liver MAO of terrestrial mammals, deaminates tyramine, tryptamine, dopamine, serotonin, noradrenalin, benzylamine, ß-phenylethylamine, and N-methylhistamine, does not deaminate histamine and is not inhibited by 10 mM semicarbaside. Tacrine, acriflavine, proflavine, acridine orange, and pyronin G have been established to be irreversible inhibitors of intermediate strength with respect to the tunny liver MAO. Specificity of action of the inhibitors at deamination of different substrates was identical.

[Comparative enzymological study of catalytic properties of sturgeon fish liver monoamine oxidases].

We performed comparative study of substrate and inhibitor specificity of liver monoamine oxidases (MAO) of the giant sturgeon Huso huso, starred sturgeon Asipenser stellatus, Persian sturgeon Asipenser persicus, and Russian sturgeon Asipenser gueldenstaedtii. Results of the substrate-inhibitor analysis with use of inhibitors chlorgilin and deprenil, as well as of five specific substrates indicate homogeneity of these enzymes. All studied MAO have several orders higher sensitivity to chlorgilin than that to deprenil, the essential interspecies differences being observed. There are determined kinetical parameters of enzymatic deamination (K(M) and V) of tyramine, serotonin, noradrenalin, benzylamine, beta-phenylethylamine, and N-methylhistamine. It is found that all studied enzymes show the higher activity toward serotonin and noradrenalin--substrates of the MAO form A, as compared with benzylamine, beta-phenylethylamine, and N-methylhistamine--substrates of the MAO form B of mammals, the maximal activity being shown by enzyme of the giant sturgeon.

[Substrate-inhibitory analysis of monoamine oxidase from hepatopancreas of the octopus Bathypolypus arcticus].

Study of the substrate-inhibitory specificity of mitochondrial monoamine oxidase (MAO) of hepatopancreas of the octopus Bathypolypus arcticus revealed distinctive peculiarities of catalytic properties of this enzyme. The studied enzyme, on one hand, like the classic MAO of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, beta-phenylethylamine, while, on the other hand, deaminates histamine and does not deaminate putrescine--classic substrates of diamine oxidase (DAO). Results of the substrate-inhibitory analysis with use of chlorgiline and deprenyl are indirect proofs of the existence in the octopus hepatopancreas of one molecular MAO form. Semicarbazide and pyronine G turned out to be weak irreversible inhibitors, four derivatives of acridine--irreversible inhibitors of the intermediate effectiveness with respect to the octopus hepatopancreas MAO; specificity of action of inhibitors at deamination of different substrates was equal.

[Catalytic characteristics of monoamine oxidase of whitefish Coregonus lavaretus ludoga].

Study of substrate-inhibitory specificity of liver mitochondrial monoamine oxidase (MAO) of sexually mature individuals of the whitefish Coregonus lavaretus ludoga P. from the Ladoga Lake has revealed distinguished peculiarities of catalytical properties of this enzyme. The studied MAO, on one hand, like the classical enzyme of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, and beta-phenylalanine, but, on the other hand, to deaminate histamine, the classic substrate of diamine oxidase. The found equal activity and sorptional ability of the enzyme toward six studied substrates including histamine, as well as results of the substrate-inhibitory analysis with use of specific inhibitors--deprenyl and chlorgilin--indicate homogeneity of the enzyme. The detected for the first time among the fish MAO wide substrate specificity and an unusually low sensitivity to both studied acetylene inhibitors does not allow ascribing unanimously the studied enzyme to the known MAO forms of organs and tissues of homoiothermal organisms. Apparently, the revealed enzyme form of poikilothermal organism is not the true MAO, but performs a large amine oxidase function.

[Comparative sensitivity of liver monoamine oxidases of frog and whitefish to some tricyclic compounds].

There is performed a comparative analysis of action of four acridine derivatives and of one xanthene derivative (pyronine G) on activity of liver monoamine oxidase (MAO) of two species of poikilothermal freshwater animals: a representative of amphibians--the common frog Rana temnporaria and a representative of the order Salmonidae--the European whitefish Coregonus lavaretus. The studied synthetic hexamerous tricyclic compounds show the irreversible character of inhibition of intermediate potency towards the enzyme from both biological sources. There are obtained qualitative and quantitative differences in the reactional ability and selectivity of action of the studied inhibitors for liver MAO of frog and whitefish. The obtained data of the inhibitory analysis with use of specific substrates are an indirect proof for the existence in liver of the studies frog species of two molecular forms, whereas in the whitefish liver--single molecular MAO form.

[Comparative enzymological study of catalytic properties of liver monoamine oxidases in frogs].

Comparative enzymological study of catalytical properties of monoamine oxidase (MAO) of liver of the lake frog Rana ridibunda and brown frog Rana temporaria has revealed certain features of similarity and differences between these enzymes. The MAOs from both studied biological sources show catalytic properties resembling those of the classical MAO of terrestrial vertebrates: they deaminate tyramine, tryptamine, serotonin, benzylamine and do not deaminate histamine, have sensitivity to chlorgiline, the specific inhibitor of the MAO A form, and deprenyl, the specific inhibitor of the MAO B form, and are not inhibited with 10(-2) M semicarbazide. Based on data of substrate-inhibitor analysis, a suggestion is put forward about the existence of two molecular forms of the enzyme in liver of the studied frog species. Interspecies quantitative differences have been revealed between liver MAO of Rana ridibunda and Rana temporaria in values of kinetic parameters of reactions of deamination of several substrates and in sensitivity to the inhibitors, deprenyl and clorgyline. In the species Rana temporaria the MAO activity in reaction of deamination of serotonin and benzylamine were practically identical, whereas in the species Rana ridibunda these parameters for serotonin were almost one order of magnitude higher than for benzylamine. For the species Rana ridibunda, selectivity of action of deprenyl was expressed many times weaker while selectivity of the chlorgiline--one order of magnitude stronger than for the species Rana temporaria. The catalytic activity for all studies substrates of liver MAO of both studied amphibian species were several times lower as compared with the enzyme of rat liver.